Which of the following is a factor of rs + tr - pt - ps?<...
Which of the following is a factor of rs + tr - pt - ps?
(p - s)
(s - p)
(r - p)
(r + p)
Correct answer is C
rs + tr - pt - ps = rs - ps - tr - pt = (r - p)s + (r - p)t = (r - p)(s + t), hence r - p is a factor